1. Field of the Invention
The present invention relates to the field of switched telephony, and in particular, to digital cross-connect systems and methods by which calls are routed through digital cross-connect systems.
2. Background of the Invention
Conventional telephone network systems route calls from subscriber equipment (sometimes referred to as customer premise equipment or xe2x80x9cCPExe2x80x9d) to a local network or long distance carrier using hard-wired connections in a digital cross-connect system. Typically, the digital cross-connect system (xe2x80x9cDCSxe2x80x9d) receives DS-3 lines and connects them to fixed outgoing lines to call carriers. The DS-3 lines typically contain twenty-eight T-1 lines, which in turn each typically contain twenty-four DSO lines. Thus, the typical DCS receives a total of 672 DSO lines (24 xc3x9728) and routes them to 672 outgoing lines. The DCS has no switching capabilities and merely routes incoming calls based on the hard-wired connections to outgoing lines. This routing is determined at the time of installation and cannot be remotely altered or programmed.
Because the DCS lacks routing capabilities, all calls received from a particular DSO line are routed to the same outgoing line. The outgoing line is connected to a specific call carrier, e.g., local or long distance, that handles the routing of the call from that point forward. The DCS routes an individual call to the specified carrier regardless of whether the service is optimal for that call. Thus, for example, if a DSO line is hard-wired to a local network, an incoming long distance call must first go to the local network and then be switched to a long distance carrier. Thus, because all calls are routed the same way, a telephone service subscriber can not specify a particular carrier for a particular type of call.
Subscribers to a single DSO line are faced with two call routing options: (1) send all calls from a particular DSO line to a local network or (2) send all calls from a particular DSO line to a long distance carrier. Each option presents considerable drawbacks.
The first option sends all calls to the local network and has the local network switch long distance calls to a long distance carrier. Because the switching is completed within the local access transport area (the xe2x80x9cLATAxe2x80x9d), this method is considered xe2x80x9cswitching trafficxe2x80x9d, and is subject to switch origination and termination hi fees imposed by federal regulation. Thus, by not directly accessing a long distance carrier, the subscriber may pay unnecessary fees for using long distance service.
The second option sends all calls to the long distance carrier for switching. In this case, the long distance carrier must switch local calls to local networks and therefore burden the subscriber with extra switching charges.
For subscribers of multiple DSO lines, the additional lines offer only a moderate increase in call routing flexibility. Multiple line subscribers have the following options: (1) dedicate certain DSO lines to local networks and other DSO lines to long distance carriers or (2) use subscriber equipment to internally route calls to specific DSO lines connected to local or long distance lines. However, once again, each option presents disadvantages.
The first option connects certain incoming DSO lines to local carriers and other DSO lines to long distance carriers. These designated connections require the subscriber to predict how many local and long distance calls will be made at any one time. Once connections are made based on this prediction, the subscriber must monitor its callers to ensure that the callers are using the appropriate lines for particular calls (i.e., local calls on lines connected to local networks and long to distance calls on lines connected to long distance carriers). Further, if the subscriber""s calling patterns change, such that the demand for local or long distance calls exceed the available lines, the subscriber must go through the costly and time consuming exercise of changing or adding to the hard-wired DCS connections. In the end, because of problems with caller error or capacity problems, calls are often routed to an inappropriate service, which must then switch the call and incur additional fees.
The second option is also not a complete solution. To better coordinate the access of outside lines and to avoid unnecessary switching charges, subscribers sometimes use Private Branch Exchange (xe2x80x9cPBXxe2x80x9d) equipment to internally switch and connect calls to the appropriate local or long distance network lines. The PBX equipment evaluates the type of call being made from the subscriber premises and chooses the DSO line connected to the service appropriate for the call type. Although this technique reduces unnecessary switching charges, the purchase, installation, and operation of PBX equipment itself is quite expensive.
Additionally, the PBX equipment does not completely solve the line capacity problem. If, for example, all of the subscriber""s long distance lines are in use, the PBX will route a long distance call to a local network line. As a result, the subscriber pays for the local network to switch the call to another long distance carrier and loses the discounts the subscriber would have received by using the dedicated long distance lines.
In response to the drawbacks of the above four options, one solution could be to have the local exchange company provide long distance service through its switch, e.g., central office. However, federal regulations prohibit certain local exchange carriers from switching calls in this manner.
Thus, there remains a need for a routing system that classifies and routes calls before they reach an inter-LATA central office and are subject to switch origination and termination fees. The routing system should recognize the subscriber from whom a call is coming, should determine the appropriate carrier for the call, and should route that call to the line of the appropriate call carrier. The routing system should be able to accommodate varying demands for particular local or long distance services without exceeding the capacity of the outgoing lines. Further, to comply with federal regulations, the routing system must not use the switch or central office of a local exchange company to provide the service.
The present invention is a call routing system that enables local exchange carriers to route calls to specific carriers before the calls enter the inter-LATA region and become subject to unnecessary switching-fees. The call routing system receives a call, identifies the subscriber and the type of call, determines the preferred call carrier, and routes the call to a line connected to the preferred call carrier, all before the call enters the inter-LATA region. The present invention affords subscribers the flexibility both to connect with the carrier most appropriate for the type of call being placed and also to access as many carrier lines as required to handle increased call traffic.
A preferred embodiment of the present invention is shown schematically in FIG. 1. The preferred embodiment comprises a DCS, a computer with a database (hereinafter referred to as xe2x80x9ccomputerxe2x80x9d), and a service management system. For connections, the DCS has an incoming and outgoing terminal, the computer has a data input, a data output, and a programming input, and the service management system has a programming output. The incoming terminal of the DCS is connected to the subscriber equipment on one side and the data input of the computer on another side. The data output of the computer is connected to the outgoing terminal of the DCS. The outgoing terminal of the DCS is connected to the outgoing lines to the local and long distance networks. The programming output of the service management system is connected directly to the programming input of the computer.
As shown in FIGS. 2-3, the call flow is as follows. A call originating from the subscriber equipment travels through a DSO line and enters the DCS at the incoming terminal. The incoming terminal sends to the computer the call and trigger information corresponding to the call. The computer processes the call using the trigger information and sends the call with corresponding routing instructions to the outgoing terminal of the DCS. The DCS routes the call to the outgoing line designated by the computer. The call travels through the outgoing line to the local or long distance network preferred by the subscriber. The service management system is not involved in the call routing and is only used to set up or modify the subscriber preferences that govern the computer processing.
Managing calls through the computer allows a local exchange company to provide routing functions before calls enter the inter-LATA region and incur the federally imposed switching origination and termination fees. As an advantage to both the local exchange carriers and the subscribers, the present invention allows the local exchange carriers to provide local and long distance service together in a cost-effective package. In addition, by using a DCS and computer instead of switches, this routing method complies with federal prohibitions against providing long distance services through local exchange company switches.
The present invention also enables telephone subscribers to create custom-calling plans that route particular calls to designated local networks or long distance carriers. The invention recognizes the subscriber originating a call and assigns the call to the outgoing line specified by the subscriber""s calling plan. Using a routing table, the outgoing line chosen by the computer is customized to suit the subscriber""s call preferences based on variables such as the calling number, the exchange number, the time of day, the day of the week, or any number of other factors.
The present invention also eliminates the capacity problem subscribers currently face. Because the outgoing DCS terminations are not dedicated to a particular subscriber or incoming DSO line, the present invention can accommodate varying subscriber usage and always have lines available for local and long distance service.
In a preferred embodiment of the present invention, the DCS provides dial tone emulation to the subscriber equipment. This dial tone emulation substitutes for the dial tone that is typically furnished in a conventional routing system by the local or long distance network connected to the subscriber equipment through the DCS. For the present invention, when the DCS is altered to route calls through the computer, the dial tone is sent by the DCS instead of the local network or long distance carrier.
As shown in FIG. 3, in providing a dial tone, the computer monitors the line from the subscriber equipment to the DCS for an off-hook trigger. When the trigger is received, the computer sends a dial tone to the subscriber until a button is pushed on the telephone. The dial tone emulation operates to provide the caller with the dial tone the caller is expecting to hear, but does not affect the routing functions of the present invention.
Accordingly, an object of the present invention is to provide a call routing system that substitutes for routing long distance service through a switch, e.g., a central office.
It is another object of the present invention to provide a system that routes calls to appropriate carriers before the calls enter the inter-LATA region and become subject to switching origination and termination fees.
These and other objects of the present invention are described in greater detail in the detailed description of the invention, the appended drawings and the attached claims.